Not Applicable.
Not Applicable.
1. The Field of the Invention
The present invention relates generally to oil production, and more particularly, but not necessarily entirely, to a process and apparatus for liberating oil from oil shale, while generating excessive volumes of carbon monoxide.
2. Description of Related Art
The concept of releasing oil from oil shale is well known. xe2x80x9cOil shalexe2x80x9d is a naturally occurring sedimentary rock, typically a black or dark brown shale or silt-stone, that is rich in petroleum hydrocarbons, and other materials generally associated with the definition of the broad term xe2x80x9cpetroleum,xe2x80x9d xe2x80x9ckerogenxe2x80x9d or xe2x80x9cbitumen,xe2x80x9d from which shale oil can be obtained. The shale oil is produced from the petroleum hydrocarbons, and released from the shale, through pyrolysis, which refers to the subjection of the oil shale to very high temperatures. The petroleum hydrocarbons are released initially in gaseous form. After being cooled they are bituminous-like in form, as they will not flow unless heated to about 400xc2x0 or more.
Producing commercial quantities of oil from oil shale remains cost prohibitive. The world continues to procure fuel oil by pumping crude oil from natural reserves, and refining the crude. Rapid increases in the price of crude oil, and the continued depletion of our natural oil reserves, may change that.
Large quantities of oil shale reside throughout the world. In the United States, substantial oil shale deposits are found in Colorado, Utah, Wyoming and Texas. The usual process of releasing oil from the oil shale, though it has been cost prohibitive from a commercial standpoint, comprises mining the shale, crushing it, and conducting pyrolysis by subjecting the crushed shale to heat at temperatures of 1000xc2x0 F. -1400xc2x0 F. The pyrolysis phase is conducted in the form of xe2x80x9cdestructive distillation,xe2x80x9d a process by which organic substances such as oil shale, wood or coal are decomposed by heat in the absence of air and distilled to produce useful products, in this case, oils. Other products such as coke, charcoal and gases are also the result of destructive distillation.
The liberation of oil from the oil shale by destructive distillation causes considerable coking of the oil shale residue, leaving behind a xe2x80x9cretorted oil shale.xe2x80x9d The term xe2x80x9ccokingxe2x80x9d refers to the production of coke, which is the solid residue of impure carbon obtained from carbonaceous materials such as oil shale, bituminous coal and the like, after removal of volatile material by destructive distillation.
The phrase xe2x80x9cretorted oil shale,xe2x80x9d as used herein, is a form of coke, and refers to oil shale that has been subjected to destructive distillation to liberate the petroleum hydrocarbons, or oils, leaving an inorganic residue containing carbon. Therefore, the phrases xe2x80x9cretorted oil shale,xe2x80x9d xe2x80x9ccarbon residue,xe2x80x9d and xe2x80x9ccarbon containing material,xe2x80x9d as used herein, are related in meaning, and as used herein, are interchangeable.
The phrase xe2x80x9cspent oil shale,xe2x80x9d as used herein, refers to oil shale from which petroleum hydrocarbons and carbon have been removed.
The term xe2x80x9cfluid,xe2x80x9d as used herein, shall refer broadly to both liquids and gases.
Attempts have been made in the prior art to improve upon the process of liberating oil from oil shale. Many such attempts are described in the following U.S. patents, which are incorporated herein by reference: U.S. Pat. No. 4,028,222 (granted Jun. 7, 1977 to Prull); U.S. Pat. No. 3,503,868 (granted Mar. 31, 1970 to Shields); U.S. Pat. No. 4,548,702 (granted Oct. 22, 1985 to York et al.); U.S. Pat. No. 4,536,278 (granted Aug. 20, 1985 to Tatterson et al.); U.S. Pat. No. 4,505,809 (granted Mar. 19, 1985 to Brunner et al.); U.S. Pat. No. 4,304,656 (granted Dec. 8, 1981 to Lee); U.S. Pat. No. 3,652,447 (granted Mar. 28, 1972 to Yant); U.S. Pat. No. 3,941,423 (granted Mar. 2, 1976 to Garte); and U.S. Pat. No. 4,357,231 (granted Nov. 2, 1982 to Estes et al.).
It is noteworthy that none of the prior art known to applicant provides an apparatus or method that optimizes the use of heat, and the reactants in the combustion cycle, in a more efficient manner. There is a long felt need for a destructive distillation process applicable to oil shale that is capable of (i) employing a recurring combustion/reaction cycle for a longer period of time by minimizing the presence of nonessential gases, (ii) recovering unused heat instead of permitting the heat to escape into atmosphere, and (iii) reusing and regenerating some of the reactants in the process.
The prior art is thus characterized by several disadvantages, or long-felt needs, that are addressed by the present invention. The present invention minimizes, and in some aspects eliminates, the above-mentioned failures, and other problems, by utilizing the methods and structural features described herein.
It is therefore an object of the present invention to provide a process and apparatus for extracting oil from oil shale that is simple in design and operation.
It is another object of the present invention, in accordance with one aspect thereof, to provide such an apparatus that can produce an excess of carbon monoxide for use as a commercial fuel in other industries.
It is an additional object of the present invention, in accordance with one aspect thereof, to provide such an apparatus that minimizes the presence of gases that are nonessential to the extraction of oil from oil shale.
It is a further object of the present invention, in accordance with one aspect thereof, to provide such an apparatus that is capable of recovering unused heat produced in a combustion phase of the oil extraction process.
It is an additional object of the invention, in accordance with one aspect thereof, to provide such an apparatus in which a reactant in the process is regenerated and is reusable in the process.
The above objects and others not specifically recited are realized in a specific illustrative embodiment of a process and apparatus for extracting oil from oil shale. Crushed oil shale is transported into a combustion chamber, along with relatively pure oxygen and carbon monoxide which are combusted to heat the oil shale sufficiently to release petroleum hydrocarbons, leaving a retorted oil shale containing a carbon residue. The products of the combustion phase combine with the carbon residue to generate a recurring combustion/reaction cycle in which the carbon monoxide and oxygen are combusted to form carbon dioxide while retorting the oil shale by heat, and the carbon dioxide reacts with the carbon residue in the retorted oil shale to regenerate a carbon monoxide by-product. The petroleum hydrocarbons are cooled and processed into useable oils. The regenerated carbon monoxide by-product can be re-routed back to the combustion area of the combustion chamber and reused, or it can be used in whole or in part in some separate application, even as a commercial fuel in other industries. Heat that is released from the petroleum and carbon monoxide by-product during the cooling phase can be recovered, transferred back to the combustion chamber and reused. The combustion chamber is preferably sealed, enabling users to combust relatively pure oxygen in the combustion phase (instead of ambient air) to thereby reduce, and perhaps even eliminate, nitrogen and other non-essential gases from accumulating and inhibiting the combustion/reaction cycle.
An advantage of this process is that no carbon dioxide, nitrogen, or nitrous oxide gases are released into the atmosphere. The fact that the regenerated carbon monoxide gases is of a quality that can be used as a useful fuel results in avoiding exhaust gases being emitted into the atmosphere.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by the practice of the invention without undue experimentation. The objects and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims.